PREVENTIVE METHOD AND APPARATUS AGAINST BACKWARD CHARGING OPERATION

摘要

PURPOSE:To protect an interconnection with a simple apparatus and make it possible to break the interconnection between a solar power generating system and a commercial distribution line safely. CONSTITUTION:A solar power generating system 1 is connected to a commercial distribution line 3 and a low-voltage load 4 at an interconnection 2. The commercial distribution line 3 can be used for supplying an AC voltage to a low-voltage consumer after the voltage is lowered by a pole mounted transformer 31. A backward charge preventive unit comprises a current control-type inverter 12, an interconnection connector 13, and an operation control unit 15. The current control-type inverter 12 is used for converting the power from a solar cell 11 into AC power and stopped in operation by a stop control signal (an inverter stopping signal (Ss)). The interconnection contactor 13 is opened by a stop signal (an interconnection contactor parallel-off signal (So)). When the operation control unit 15 detects an increase in harmonic voltage, which is caused by a power failure in transmission at a substation 5, and the increase is over a given value the operation control unit 15 generates a stop control signal.